Dr. Feodor Orloff / Prof. John Dearborn
Bela Lugosi
Det. Insp. Larry Holt
Hugh Williams
Police Sgt. Walsh
Bryan Herbert
Morrison, undercover detective
Charles Penrose
Orloff's Secretary
Julie Suedo
Diana Stuart
Greta Gynt
Lieutenant Patrick O'Reilly
Edmon Ryan
Blind Jake
Wilfred Walter
Dumb Lou
Arthur E. Owen
Fred Grogan
Alexander Field
Henry Stuart
Gerald Pring
Prof. John Dearborn (voice)
O.B. Clarence
Police Constable Griggs
May Hallatt
Director
Walter Summers
Screenplay
Novel
Edgar Wallace
Producer
John Argyle
Patrick Kirwan
Director of Photography
Bryan Langley
Original Music Composer
Guy Jones